Power amplifier arrangements having an antenna are used, for example, in the transmission paths of mobile radios. Mobile radios are subject to an increasing requirement for a wider bandwidth in the radio-frequency signal processing. For example, mobile radios based on the GSM standard (Global System for Mobile Communication) nowadays normally already have three transmission and reception bands. Appliances such as these are also referred to as triband appliances. Accordingly, particularly at the end of the transmission path, where the power amplifier arrangement with the antenna is normally arranged, there is a requirement for these components to be designed with a particularly wide bandwidth. Even more frequency bands will be added in future mobile radio standards such as UMTS, Universal Mobile Telecommunications System, and WLAN, Wireless Local Area Network, so that an even wider bandwidth will be required.
Impedance matching must normally be carried out between the output of the power amplifier and the antenna. The increasing number of frequency bands means that the complexity of the impedance transformation from the impedance of the active power amplifier to the antenna impedance is becoming ever greater.
The amount of data being processed is also rising at the same time, in particular not only in the so-called download or downstream, that is to say from the base station to the mobile terminal, but in particular also in the opposite direction from the mobile terminal to the base station, that is to say upstream or in the upload. The power requirement of such mobile radios is accordingly also increasing continuously. It is therefore necessary to design the impedance matching between the antenna and the power amplifier not only to have a wider bandwidth, but also to provide more efficient power matching.
Transformation networks for impedance matching are nowadays normally designed with discrete inductances and capacitances. These components themselves in turn cause a not inconsiderable power loss: